private static PrivateKey parseKey()

in jsign-core/src/main/java/net/jsign/PVK.java [142:169]

• 21 lines of code
• 2 McCabe index (conditional complexity)

    private static PrivateKey parseKey(byte[] key) throws GeneralSecurityException {
        ByteBuffer buffer = ByteBuffer.wrap(key);
        buffer.order(ByteOrder.LITTLE_ENDIAN);
        
        if (!startsWith(key, RSA2_KEY_MAGIC)) {
            throw new IllegalArgumentException("Unable to parse the PVK key, unsupported key format: " + new String(key, 0, RSA2_KEY_MAGIC.length));
        }
        
        buffer.position(buffer.position() + RSA2_KEY_MAGIC.length); // skip the header
        
        int bitlength = buffer.getInt();
        BigInteger publicExponent = new BigInteger(String.valueOf(buffer.getInt()));
        
        int l = bitlength / 8;
        
        BigInteger modulus = getBigInteger(buffer, l);
        BigInteger primeP = getBigInteger(buffer, l / 2);
        BigInteger primeQ = getBigInteger(buffer, l / 2);
        BigInteger primeExponentP = getBigInteger(buffer, l / 2);
        BigInteger primeExponentQ = getBigInteger(buffer, l / 2);
        BigInteger crtCoefficient = getBigInteger(buffer, l / 2);
        BigInteger privateExponent = getBigInteger(buffer, l);
        
        RSAPrivateCrtKeySpec spec = new RSAPrivateCrtKeySpec(modulus, publicExponent, privateExponent, primeP, primeQ, primeExponentP, primeExponentQ, crtCoefficient);
        KeyFactory factory = KeyFactory.getInstance("RSA");
        
        return factory.generatePrivate(spec);
    }